In regard to the thyroid hormones, we found that TSH in the high fluoride group was notably increased (P = 0.03), whereas T4 was somewhat decreased but did not reach statistical significance (P = 0.06). However, the individual values of thyroid hormones were all within the normal range. For children exposed to high fluoride drinking water, the mean IQ value was notably decreased, whereas the percentage of poor IQ (IQ scores fell below the normal range of 90) was markedlyincreased, when compared with those of control cohorts (both P < 0.01).